Wheelchairs for invalids such as handicapped or aged people are commonly constructed of a frame supported by a large pair of main wheels and a smaller pair of steering caster wheels normally located forwardly of the main drive wheels. A stationary positioned seat and back assembly is affixed to the frame so that a user is provided support while being transported about in the chair. However, such chairs are relatively uncomfortable for prolonged usage, especially for the aged.
It is known that a rocking motion can render therapeutic and/or relaxing benefits for invalids and aged persons who are commonly confined to a wheelchair for their transportation because they are not ambulatory. Therefore wheelchairs have been developed to provide users with the benefits of a rocking motion. One example of such rocking wheelchairs is described in U.S. Pat. No. 4,641,848, issued to Robert Ayers on Feb. 10, 1987 which discloses a form of rocking wheelchair developed to provide a comfortable alternative to existing wheelchairs. Ayers' wheelchair is somewhat similar in design to existing wheelchairs, but has a rockable seat attached to its frame by pivot connections at each side. Springs are attached to the seat and the frame to serve as a bias means to maintain the seat in a generally horizontal alignment when the chair is unoccupied.
Although the Ayers wheelchair provides a comfortable rocking seat, its manufacture requires a great deal of precision which is a disadvantage for production of the chair in large volumes. U.S. Pat. No. 5,004,259, issued to Ayers et al. on Apr. 2, 1991 discloses an improved rocking wheelchair formed of a frame, two sets of support wheels for the frame, and a seat portion rockably connected to the frame by a rocking assembly. The rocking assembly includes a pair of leaf springs extending horizontally and connected by respective upper and lower strip means to the seat portion and the frame in order to maintain the seat in a generally horizontal alignment when the chair is unoccupied, and permit the seat to rock with respect to the frame. Rx-Rocker Corporation which is the assignee of U.S. Pat. No. 5,004,259 has further improved on the Ayers et al.'s rocking wheelchair with vertically positioned leaf springs and frictional locking means to lock the seat in a tilt position.
Nevertheless, as the demand for wheelchairs increases, concerns arise regarding aspects of, for example safety, adjustability and user/caregiver convenience. Therefore, there is a need for further improved rocking wheelchairs.